1. Field of the Invention
This invention relates to a size-reduction apparatus installed in a pipeline, and more particularly to a piece of equipment designed to reduce materials transported in a pipeline to a consistent mixture prior to further processing.
2. Description of the Prior Art
The manufacture of a wide variety of materials requires the use of some type of size-reduction equipment in order to make their subsequent transport and reaction processes more efficient and cost-effective. It is therefore required that equipment be available to control the particle size, minimize the down-time when maintaining or replacing the unit and to maximize the flow characteristics.
There are a number of manufacturers currently producing size-reduction equipment, although few have a design suitable for installation in a pipeline. Nearly all these pipeline-installable machines use a similar principle to reduce the materials as they pass through. Cutter blades rotating around a common shaft pass through slots in a stationary bar or between rotating blades moving at a speed different than the cutter blades. The resulting particle size is equal to or less than the distance between the stationary or slow moving blades
Presently, size-reduction equipment used to transport materials in a pipeline from one location to another has several process and cost-related inadequacies.
Firstly, for many of the prior art machines, in order to perform repair, maintenance, and replacement work, the entire unit must be removed from the pipeline. Such a machine is disclosed in U.S. Pat. No. 3,556.421 ("Chopping Machine"). This necessitates that the process flow be shut down for a significant period of time while the corrective maintenance is underway. The shutdown may be avoided if a bypass is incorporated in the design. The bypass permits an alternate path for the flow while the size-reduction unit is being serviced. However, the bypass greatly complicates the piping design and the bypass's size physically limits those locations where the size-reduction unit may be placed in the pipeline.
Another disadvantage of the design of many size-reduction machines is caused by the cutting/crushing unit's interruption of the flow in the pipeline. At the cutting/crushing unit, the pipeline's effective cross-sectional area is decreased causing a significant decrease in the flow, and a decrease in the amount of material that is processed. Correspondingly, the amount of energy required to process the material through the cutting/crushing unit is increased, the process time is longer, and additional wear and tear on the size-reduction unit results.
Lastly, another disadvantage of currently available size-reduction equipment is the difficulty and costly maintenance operations due to the relative inaccessibility of the working components, such as seals, bearings, and cutters. In addition, many units employ welded components which when damaged, cause progressive damage to all parts connected.
Prior art does disclose a size-reduction machine in which the cutting/crushing unit is removable from the pipeline without interrupting the pipeline's integrity. This machine is disclosed in U.S. Pat. No. 3,976,252 ("Chopping Machine"). However, this machine's stationary blade set-up is quite complex. The stationary blades are a series of blades mounted around a rotating shaft, alternating with the individual cutting/crushing blades. The stationary blades are prevented from rotating by a pair of retaining lugs precisely positioned along the inside of the machine's housing. Servicing this cutting/crushing unit requires removing the cutting/crushing unit, removing the individual blades (both stationary and cutting/crushing) from the rotating shaft, and reinstalling all the blades back on the rotating shaft. This procedure is difficult and time-consuming: the cutting/crushing unit is not designed for removal from and installation in the pipeline as a single, integral unit. Accordingly, final adjustments must be done during actual installation of the cutting/crushing unit in the pipeline. Consequently, spare cutting/crushing units cannot be serviced and adjusted at a central maintenance site and stored in inventory for immediate installation when needed.
Furthermore, as disclosed in this patent, the bearings and packing between the stationary blades and the rotating shaft tends to wear away during operation and contaminate the flow. Such contamination may be unacceptable. Also, over time, this wearing away will cause the blades to loosen relative to each other, resulting in catastrophic damage to the unit: the blades eventually intermeshing and damaging the cutting/crushing unit beyond repair.
In short, the prior art devices are generally cumbersome to install, complicated to service, detrimental to pipeline flow, or require significant amounts of pipeline downtime during servicing.